Electric sign



Patentecl July 1, 1930 ora` srrs TE kosrcs FRANK G. DIFFIN, or DAYTON, oHIo, `assreruon vTo THE LoNGsIGN CORPORATION, or' DAYTON, oHIo, A CORPORATION or oHIo v:ELEGTRIC VSIGN' Application filed November 21, 1927. Serial No. 234,723.

This invention relates to electric signs of the type having a series of lamps ywhich are Villuminated in suchl a way as to produce Words or other visual indications travelling along the sign.

One of the principal objects of the invention is to provide means for increasing the distinct-ness of appearance of the travelling words or characters, so that they may be more easily 'distinguishedz 1 Another object of the invention is to provide as such means a colored or translucent screen positioned adjacent the series of lamps and between the lamps and the eyes of the observer.

Other objects and advantages of the invention will be apparent from the following description and from the drawings in which- Fig. 1 is an elevation of an electric sign embodying the present invention, part of the screen being broken away;

Fig. 2 is a transverse section through the sign; and I Fig. 3 is a view of a fragment of one form of screen of the present invention.

The invention pertains particularly to an electric sign embodying a bank of lamps adapted to be illuminated to form letters, words or other signals which travel across the sign, the control of the lamps being effected by means of a controller such as a perforated tape Which controls the various circuits to the lamps as more fully set forth in the prior patent of John E. Long No.

1,572,212 dated February 9, 1926. It has been found that according to prior constructions in which the lamps themselves are clearly visible to an Observer, and are separated from the eye only by means of a transparent colorless glass that the characters or letters, particularly when viewed from a short distance are at times'quite blurred and indistinct so that they may not be read or distinguished easily. Because of the speed of travel of the characters across the bank of lamps as successive lamps are illumnated and extinguished the light effect appears to trail, or in other words each part of a character or letter appears to be of undue width, somewhat the same effect as is given when a firebrand yor 'light is moved rapidl-y-the image apparently persisting after the light has moved on. Each letter travelling across 5.5 the sign is Vmade up of a'number of such 'spots of light and when an Observer views the travelling indications of the sign, even after a particularlamp has grown dark and the next lamp in advance has been illuminated, '6.0 `he appears to still see the darkened lamp, as the nerves of the eye have been so affected that the vision is retained even after the Vlamp has gone out. He thus appears to see or retain this vision of the previously illuminated lamp along with the next lamp which is brightened and't-hus each line of the indi- .catons or letters appears to be of undue width. This apparent undue width of the lamp mayalso be caused by the substantial 7:0 length of time that it takes for an illuminated lamp to become totally dark. After the current has been cut ofl' of apartic-ular lamp it takes some little time yfor the Vheat of the filament to be dissipated and vconsequently a fract-ion of a Vsecond after the current has been cutoff fromI the. lamp the latter still glows dimly. Also the visual interference due to a number of small lamps Shining and moving .at the same time adds to the confusing efiect. When a suitable screen is placed -in front ofxthe lamps it haszthe effect ofovercoming this objectionable confusion whereby -to obtain letters or signals which are more distinct and more easily read.

In the drawings the sign designated generally 10 is shown havinga bank of lamps 11 which are arranged in closely spaced .rows, and the electrical circuits from the various lamps are controlled by means of a tape in a :9 Vmanner as fully described lin the prior patent of John E. Long No. l,572,212 previously mentioned. The lamps. yare illuminated in .suchy a way as to produce'letters or words .95

orother visual-indicationswhich travel from ,the observer7s .fright'to left along the sign, each lamp being illuminatedffor a veryshort :time and .then being darkened .While succes- -s'rve :lampsfa-re illumina'ted :to produce the :1:09

on the eyes.

continuously travelling effect of the indication desired.

In front of the bank of lamps 11 is a screen 12. Thi's screen is preferably colored and it has been found that a green or red color is very effective and produces a pleasing effect The screen is preferably some- What translucent and cuts down the visibility of the lamps themselves to an Observer, and so produces clear signals, easily distinguished even at very short distances. Such a color screen in front of the indications somewhat reduces the intensity of the various points of illumination and thus reduces the efi'ect of the small concentrated sources of light on the eye, so that the persistency of vision is somewhat cut down and the eye is permitted to view the changing character of the signals without retaining an apparent view of previously illuminated sources of light. The apparent width of any particular line or character of the sign is thus reduced, as far as its effect on the eye is concerned, and the signals are produced in a more distinct manner so that they may be more easily read. The use of a screen which is provided with a suitable color such as green, is also effective in reducing the apparent trail of the signals. This may be due to the fact that a color screen of this character prevents the passage of light rays from a lamp as soon'as it begins to become dim. Consequently after the current has been cut off from a particular lamp and while this lamp is becoming darkened but still retains some slight illumination which is made up mostlyof red rays of light, these red rays of light will be prevented from being observed by one viewing the sign due to the presence of the color screen in front of the lamps.

Furthermore the somewhat translucent character of the screen will hinder the passage of light from the lamps which are becoming darker but which have not yet been completely darkened, as a translucent screen does not permit a free passage of light rays through it. The effect of the screen therefore is to cause the indications or signals to be more sharply outlined, as far as the apparent optical efi'ect on the Observer is concerned so that he may more easily read the signs.

, As shown in Fig. 3 in which a fragment of 'one form of screen is set forth this screen may consist of a comparatively thin sheet 13 of a suitable cellulose derivative containing suitable coloring matter, in which is embedded a Wire mesh 14 the wires of Which are comparatively fine so that they will not materially interfere with the indications of the sign. The Wire mesh 14 gives to the screen sufiicient strength and permits the use of a comparatively thin film of the cellulose derivative. The use of a cellulose derivative as a screen produces a flexible translucent sheet of material and one which is not materially affected by the heat of the lamps. It will be apparent however that other materials may be used for the screen than the particular material which has been herein illustrated and described. Colored glass, for example, serves very satis- 'factorily While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claim.

What is' claimed is:

An electric sign having a series of lamps which are adapted to be illuminated to form visual indications travelling along the sign, and a screen in front of the sign for increasing the distinctness of the travelling indications, said screen comprising a film of translucent material supported upon a fine wire mesh.

In testimony whereof I hereto aflix my signature.

FRANK G. DIFFIN. 

